PLATO

WO'-
My involvement with the PLATO system covered the entire period
that I was a graduate student at the University of Illinois. From
1973 to 1980, I worked as a research assistant and occasionally as a
teaching assistant in the Medical Computing Lab at the School of
Basic Medical Sciences in Urbana, where my PLATO user ID was jones of rhrc
(the Regional Health Resource Center) and then jones of mcl
(the Medical Computing Lab),
also sometimes written jones/rhrc and jones/mcl.
While I was there, I did several things.

But first: Why are so many of the screen shots shown here in orange
on a black background? The answer is simple: Through the 1970's,
the dominant terminal used on the PLATO system was the Magnavox PLATO IV
student terminal. In an era when all other computer display screens
used CRTs, this display used a neon-discharge plasma panel. Yes, this
is exactly the same technology used in plasma flat-screen TV screens
today, except without the phosphors, so there was only one color, orange.

WO"'
The University of Illinois Archives maintains an on-line archive of several
early PLATO notesfiles. These were one of the first great experiments in
social media, and their archive preserves several of my early notes. The
oldest I can find is a complaint about the PLATO text editor from
12/9/1974,
when I wrote:

---------- note 614 editing!
12/09 10.37 jones rhrc
When reading a lesson,it would be nice to be able
to read directly over lesson block bounds instead
of having to back out to the lesson index and type
the letter of the next block. Mabe the -NEXT1- key
could advance to the beginning of the next block
and save changes in the previous block if not in
inspect only mode?

This takes some translation into modern terms. Since PLATO was intended as
a computer aided instruction system, all user files were referred to as
lessons, regardless of whether they served an instructional purpose. The
text editor operated on fixed-size blocks of disk space, and it was up to the
user to organize the text of a program or other document into blocks. All
PLATO terminals had function keys, -NEXT- was the name of one of them,
and -NEXT1- was the standard way to refer to the shifted version of this key.

Responses to this note indicated that indeed, system programmers on PLATO had
exactly this function available to them, but they didn't want to release it
to the general user community.

At the time, there were only 3 notesfiles in the world, one for system
announcements (world readable), one for help requests (world write only), and
one for general use (world read-write). The archive only contains the latter.
I've extracted all of my old notesfile postings from this archive
and annotated them here.

An advertising poster for the Simpler system from 1980
(author's collection). The terminal is a CDC IST-II with the
nameplate changed.

The typography of this is rather poor by modern standards. It
was printed on a Dataproducts chain printer attached to the
Modcomp IV. I had to write both the text editor and the text
formatting program needed to print it.

A year later, in May 1977, I revised the thesis slightly,
adding an additional 7 pages for release as Technical Report
UIUCDCS-R-77-868
UILU-ENG 77 1719.
This was digitized by the Internet Archive
in 2013, at a resolution higher than necessary for the chain printer
text or ballpoint-pen diagrams. They worked from a paper copy in the University
of Illinois Library that has circulation stamps indicating that it was checked
out by library patrons in 1982, 1995 and 1996.

This thesis documents what became GIST TUTOR, after Global
Information Systems Technology was founded in 1980 to market
the Modcomp PLATO/TUTOR clone. GIST originally called their
clone Simpler, but later, after rewriting my interpreter in C,
they called it ACCORD.

WO="'
The PLATO system was intended for computer-based instruction, but
it was incredibly appealing to develop games on it. Some of those
games were instructional. Airfight, the first multi-user 3-d graphical
flight simulator, really did teach flying, even though the planes
were all jet fighters and you could load them as you desired with
fuel or ammunition up to the plane's weight limit.
(There are many web pages that give pocket histories of the early
development of computer games on PLATO. See, for example,
Chapter 6
of The
Complete Wargames Handbook.)

The relationship between the system staff and game developers on
PLATO was a mixed one. On the one hand, games were a great test
of the system. On the other hand, many games were resource hogs.
PLATO was designed as a timesharing system. The machine could
execute one MIPS (Million Instructions Per Second), this made it a
supercomputer, by the terms of the early 1970's. If they wanted
to support 200 users, the average user load had to be under
5 TIPS (Thousand Instructions per Second). Most games, particularly
first-person shooters like Airfight, ran at well over 10 TIPS.

My job developing a TUTOR implementation for the Modcomp IV computer
required that I explore the TUTOR language thoroughly, and it was
natural for me to try writing a game. I set out to design a game
that had the appeal of an arcade game, and along the way, I decided
to make it run in under 5 TIPS.

The Result was HiVolts, the Game of Electric Fences, with the
title screen as shown below. My artwork for the title survived
unchanged through years of evolutionary development by later
authors who worked on the game. The core of
the game is not entirely original. Greg Chesson had recently
demonstrated Unix on campus -- it is noteworthy that Illinois
was the first licensed Unix site outside of Bell Labs; UNIX
license number 1 was granted to Illinois in 1974.
One of the things Greg demonstrated in passing was the suite of
games that came with Unix. My memory of seeing him briefly
demonstrte one of those games was the root inspiration for the
game I wrote.

This game has been preserved as hivolts on
cyber1.org, from which the following
screen shot was taken in 2008.

The preservation of HiVolts was not trivial. The credits in the
title page are explained by this quote from Dirk Pellett:
"The version of the Hi-Volts source I had on Accord (written in
GIST's version of TUTOR) ... declares you, Douglas Jones,
as the sole source of the game. I used that source to
back-translate to PLATO TUTOR so that it would run on cyber1.org."

In short, each round of play in HiVolts involves dropping the player
onto a random spot on a randomly created
game board, a field surrounded by electric fences and with fences
scattered here and there on the field. The field also contains
semi-intelligent mhos (inverse ohms, a lame in-joke) that
are attracted to the player and will eat the player if they come
too close. The player can survive by manuvering in such a way
that the mhos blunder into electric fences. You win the round if
you survive without being consumed or electrocuted until all of
the mhos have been electrocuted.

I believe one of the later authors changed the graphics for the game
itself, as illustrated above, replacing the alphabetic
symbols I had used with graphics. The original version would have presented
the above screen something like this:

The appeal of HiVolts was somewhat of a mystery to me. It isn't a first
person shooter where fast twitch reflexes lead to winning. Instead,
the game is dominated by carefully and thoughtfully running away from
the monsters in the maze. An experienced player has about even odds
of surviving one round of play.
Each round of the game was short enough that many game sessions
involved multiple rounds, and as I realized this, I made the game
compute the player's win-loss ratio for the session. Today, we
would describe HiVolts as a casual game, and it is fair to say that
it was one of the first casual games to achieve success in the
PLATO world.

Flint Pellett, one of the authors of the legendary PLATO game DND,
one of the first computerized spinoffs of Dungeons and Dragons,
worked with me in the Medical Computing Lab. He said that his
brother Dirk
was interested in HiVolts, so when
I moved on to other things, I passed the game to them.
The game had already attracted
a following, and this grew after Dirk added a record book to the game,
so that the game computed (and displayed) a list of the best players,
ordered by the win-loss ratios they had achieved.

Apparently, at some point after my involvement with HiVolts ended,
someone else modified it. Dirk Pellett remembers "a version of Hi-Volts
where the 'mhos' were lightning bolts instead of frowny-faces, there
were double-lightning-bolts that could move twice, and the fences were
NOT destroyed when a mho walked into it, all of which are different from
the version ... re-created on cyber1." This alternative version doesn't
ring any bells with me -- the double-mhos idea is particularly alien to
my memory, so obviously, the game evolved on PLATO. I'm fairly sure I'd
have given a copy of the source to anyone who asked for it back then.
Computer games had yet to become important items of commerce at the time.

When Pac-Man came out, I wondered if the developer had ever seen
the game of Electric Fences. The relationship between the Pac-Man player
and the ghosts of that game has some similarity to the relationship
between the player and the mhos of Electric Fences. Pac-Man, however
has a static maze, not the random maze of Electric Fences, and Electric
Fences has nothing analogous to the "food" dots that Pac-Man consumes.

WO"'.
Some students freeze up the first time they find themself in front of
a computer keyboard. We had this problem with medical students at
the University of Illinois School of Basic Medical Sciences, so in August,
1979, the Medical Computing Lab at the school produced a guide
for students on the use of computer assisted instruction using PLATO.
I drew this illustration for the guide, showing what the PLATO terminal
does not contain. It's a decent drawing of the Magnavox PLATO IV student
terminal. That's a flat plasma display panel in front, The bulk of the
volume is occupied by the folded light path of the rear-projection
microfiche reader in the terminal. The 6-inch wide margin around the
screen is because of the electronics around the edge of the flat panel.

TU"-
PLATO supported user-defined character sets. I knew a bit of calligraphy,
so I decided to go out on a limb and try creating a character set that
was emphatically not the usual computer-style character set. I called it
gothic, not after the modern font, but in the older sense of the
word, because it was very much the barbaric font, very unlike the humanist
fonts from which most modern typography springs.

The writable character set of the PLATO terminal had only room for so-many
capitals, so I put in only 3, made of 6 characters each, where characters
on PLATO were 8 by 16 pixels.

You'll notice that the 8 by 16 matrix forced the M to be cramped side to
side, and it forced the P to slip up a pixel or two. Those defects
were fixed in the later scalable and rotatable lineset version of the
character set.

The output of the instructional lesson I wrote
on the use of the Gothic charset and lineset is available, as it
existed in late 1976. According to the
Public notes archive for 1975
I announced the availability of Gothic on Dec. 16, 1975.
The content of that lesson, in addition to
explaining the use of the character sets, also makes it clear that this
character set had already made it into the standard character-set library
of PLATO by the time I wrote this lesson, but note also that the game of
Hangman is not mentioned. Unfortunately, no machine-readable copy of this
material appears to survive.

The output mentioned above was printed on paper using a PLATO graphics
printer. This was a remarkable impact printer using a "wobble bar" that
scanned a horizontal row of on the order of 8 print hammers rapidly back
and forth across the page, allowing it to print each of the 512 lines of
the screen in under a minute. I do remember this printer being loud.
Craig Burson wrote on Nov. 5, 2010 to remind me that Art Carroll of the
PLATO Project built the prototype of this printer using an OEM shuttle-bar
print mechanism (was it from Genicom?).
It was later marketed by CDC at the 726-10 printer. We
had one in the school of Basic Medical Sciences in Urbana.

The gothic character set was used in the educational game of Hangman
(preserved as 0hangman on
cyber1.org)
to support a rather silly back story explaining why a man was being hung
for not being able to spell.
(Hangman is preserved as 0hangman on
cyber1.org, from which the above
screen shot was taken.)
to support a rather silly back story explaining why a man was being hung
Over a decade or so, I earned about the price
of a pizza every year for this contribution to PLATO, through the micropayment
scheme PLATO supported. Hangman is copyrighted 1976 and credits me as
the designer of the typeface.

WOU"-
After I designed the Gothic lineset, someone asked me if I couldn't
do something more useful -- design a legible character set that people
would actually want to use. So, I designed a classical Roman lineset,
with decent proportional spacing. The geometry is still basically
octagonal, not round, but in the smaller sizes, it looks pretty good,
and in the larger sizes, it is far more ligible than the standard PLATO
dot matrix fonts.

The illustration here is a screen shot from
cyber1.org,
where my font is preserved in lesson linesets.
I found two
printed screenshots
in my files that I made
using the old PLATO graphics printer some time in the late 1970's.
The paper is a bit yellow, but the scanner
fixed that. If you zoom in on the PDF, you can see the impact marks
of the print hammer for each pixel of the display. The second
page of the old screenshot is a manual for the using the lineset.

One trick I used was to define backspace (shift space on PLATO) to be
just the right size to kern lower case letters under upper case
letters such as Y and T, so typing T(backspace)o or Y(backspace)es
would print To or Yes with appropriate kerning.